IIMA's ‘cool' invention may be a boon for ‘hot’ regions

The Centre for Management in Agriculture at the Indian Institute of Management, Ahmedabad, in collaboration with Fabron Airtech Engineers have installed an experimental Earth-Tube Heat Exchanger at Thor village near Sanand.

The ETHE is a device that permits the transfer of heat from the ambient air to deeper strata of soil and vice versa. ETHE is based on the well-known fact that while ambient temperatures vary cyclically, temperature of the soil beyond a depth of two metres remains virtually constant. ETHE is widely used in Europe and the US to condition (cool and heat) the air in greenhouses, poultry, and pigsty. This cooling system will bring positive results in the hot and arid areas of Saurashtra, Kutch and North Gujarat. Dr Girja Sharan developed the exchanger at the TIM, Abmedabad.

The experimental unit at Thor consists of a 50-in tube of 10 cm diameter buried 3 in deep in the ground. The tube is provided with fins to increase its heat exchange power.

A blower pumps the ambient air through the tube. When air emerges from the other end, it gets cooled to nearly the same temperature as that of the soil. Temperature of the soil at 3-m depth is 26 degree C and remained virtually constant during experiments. For example, on a day when the ambient temperature was 36 degree C, the tube was delivering air at 27 degree C. This is comparable to cooling by a desert cooler.

The tube is elaborately instrumented. Temperature sensors are installed inside the tube at the inlet, the outlet and the centre. Sensors are also installed outside the tube in the soil to permit a thorough study of its performance.

ETHE uses only a small amount of electricity to run a lower power blower. It requires very little repair and maintenance. The most significant advantage is that while it delivers air at temperature comparable to desert cooler, it uses no water at all.

ETHE can be used in farms to store onions.

Compiled from local news media